Small molecule Zn(II) complexes containing N- and S- donor environments may
serve as appropriate models for mimicking Zn protein sites, and thus, their reactions
with heavy metal ions such as Pt(II) and W(0) may provide insight into possible adduct
formation and zinc displacement. To study such possible interactions between zinc
finger proteins and platinum-bound DNA, the ZnN2S2 dimeric complex, N,N?-bis(2-
mercaptoethyl)-1,4-diazacycloheptane zinc (II), [Zn-1?]2, has been examined for Znbound
thiolate reactivity in the presence of Pt(II) nitrogen ? rich compounds. The
reactions yielded Zn/Pt di- and tri- nuclear thiolate-bridged adducts and metalexchanged
products, which were initially observed via ESI-mass spectrometry (ESI-MS)
analysis of reaction solutions, and ultimately verified by comparison to the ESI-MS
analysis, 195Pt NMR spectroscopy, and X-ray crystallography of directly synthesized
complexes. The isolation of Zn-(?-SR)-Pt-bridged [(Zn(bme-dach)Cl)(Pt(dien))]Cl
adduct from these studies is, to our knowledge, the first Zn-Pt bimetallic thiolatebridged
model demonstrating the interaction between Zn-bound thiolates and Pt(II). Additional derivatives involving Pd(II) and Au(III) have been explored to parallel the
experiments executed with Pt(II).
The [Zn-1?]2 was then modified by cleavage with Na+[ICH2CO2]- to produce (N-
(3-Thiabutyl)-N?-(3-thiapentaneoate)-1,4-diazacycloheptane) zinc(II), Zn-1?-Ac or
ZnN2SS?O, and 1,4-diazacycloheptane-1,4-diylbis(3-thiapentanoato) zinc(II), Zn-1?-Ac2
or ZnN2S?2O2, monomeric complexes (where S = thiolate, S? = thioether). The [Zn-1?]2
di- and Zn-1?-Ac mono-thiolato complexes demonstrated reactivity towards labile-ligand
tungsten carbonyl species, (THF)W(CO)5 and (pip)2W(CO)4, to yield, respectively, the
[(Zn-1?-Cl)W(CO)4]- complex and the [(Zn-1?-Ac)W(CO)5]x coordination polymer.
With the aid of CO ligands for IR spectral monitoring, the products were isolated and
characterized spectroscopically, as well as by X-ray diffraction and elemental analysis.
To examine the potential for zinc complexes (or zinc-templated ligands) to
possibly serve as a toxic metal remediation agents, Zn-1?-Ac and Zn-1?-Ac2 were reacted
with Ni(BF4)2. The formation of Zn/Ni exchanged products confirmed the capability of
?free? Ni(II) to displace Zn(II) within the N-, S-, and O- chelate environment. The
Zn/Ni exchanged complexes were analyzed by ESI-MS, UV-visible spectroscopy, IR
spectroscopy of the acetate regions, and X-ray crystallography. They serve as
foundation molecules for more noxious metal exchange / zinc displacement products.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2009-05-536 |
| Date | 2009 May 1900 |
| Creators | Almaraz, Elky |
| Contributors | Darensbourg, Marcetta Y. |
| Source Sets | Texas A and M University |
| Language | English |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | application/pdf |
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